Fig. 1 The relative importance of each major habitat type for threatened birds

Analysis of data held in IUCN 2020 Red List

Birds are found across the world in all major habitat types. Most threatened birds show a clear preference for certain types of habitat, with 37.7% occurring in just one major type (e.g. forest, grassland) and 68.1% in one or two. Forests are one of the most important habitats for birds as shown in Fig. 1, supporting an impressive 78% of threatened bird species, with 27.6% partially or exclusively supported by shrubland, 15.7% by inland wetlands, and 16.3% by grasslands. Marine habitats support a higher than expected proportion of threatened birds (12.8%), while savannas are of lower importance than expected (8.6%). Only 33.2% of threatened species use an artificial habitat (compared with 49.1% of all birds), which as would be expected suggests that threatened species may be less tolerant of habitat modification. These species depend on adjacent natural or semi-natural habitats for breeding or feeding, but are able to use human-modified habitats to some extent.

Fig 2. The importance of each major forest type for threatened birds

Analysis of data held in IUCN 2020 Red List

Threatened birds are found in all forest types; tropical/subtropical moist lowland and montane moist forest are the most important habitats supporting 47.8% and 38.1% of species respectively, with tropical/subtropical dry forest supporting 13.8%., as depicted in Fig. 2. These forest types are also the most important for threatened mammal species, highlighting their extreme importance to wider conservation efforts (Hilton-Taylor 2000). Threatened forest birds are highly dependent on intact habitat for their survival; 20.3% of all bird species can be found in degraded forest but only 10.5% of threatened birds use such habitat, and for the majority of these it is only of marginal importance. The vast majority of threatened species for which forest represents a major or suitable habitat type (89.6%) show a strong dependency on the habitat; 71.1% of all threatened birds have high or medium dependence on forest, as outlined in Fig. 3.